This invention relates to the method for making thin quality floor plate.
Steel floor plates have a wide range of useful applications, including: construction, public and private walkways, ramps, and stair treads. Steel floor plates should be sturdy and rugged providing impact resistance and feature treading to prevent slips and falls. In the past, floor plates have been relatively thick with a relatively high slip-resistant pattern to inhibit slips by users trafficking the floor plates. The effort has been to make floor plates that are thinner (and in turn much less expensive) yet are sufficiently sturdy and moveable and provide a such raised slip-resistant pattern to be effective in use.
In a twin roll caster, molten metal is introduced between a pair of counter-rotated, internally cooled casting rolls so that metal shells solidify on the moving roll surfaces, and are brought together at the nip between them to produce a solidified strip product, delivered downwardly from the nip between the casting rolls. The term “nip” is used herein to refer to the general region at which the casting rolls are closest together. The molten metal, is poured from a ladle through a metal delivery system comprised of a tundish and a core nozzle located above the nip to form a casting pool of molten metal, supported on the casting surfaces of the rolls above the nip and extending along the length of the nip. This casting pool is usually confined between refractory side plates or dams held in sliding engagement with the end surfaces of the rolls so as to dam the two ends of the casting pool against outflow.
Presently disclosed is a method for making floor plate comprising: (a) assembling a pair of casting rolls laterally disposed to form a nip between them with side dams at the end portions of the casting rolls adapted to maintain a molten metal pool supported above the nip by the casting rolls; (b) assembling a hot rolling mill downstream of the nip having work rolls with a pattern thereon forming the negative of a raised slip-resistant pattern desired in a floor plate between 0.3 and 0.7 mm in height; (c) introducing molten metal from a metal delivery system through at least one elongated metal delivery nozzle to form a casting pool supported on the casting rolls above the nip; (d) counter rotating the casting rolls to form shells on the casting surfaces of the casting rolls brought together at the nip to cast metal strip of less than 2.2 mm thickness downwardly from the nip; and (e) delivering the cast metal strip to and through the hot rolling mill to form by the negative of the slip-resistant pattern on the work rolls a raised slip-resistant pattern of between 0.3 and 0.7 mm in height in a floor plate of less than 1.7 mm thickness. Further, the delivered cast metal strip may be such as to provide floor plate greater than 0.7 or greater than 1.0 mm in thickness. The delivered cast metal strip may be silicon killed such as to provide a floor plate with less than 0.008 aluminum.